Antiseptic



Patented June 23, 1942 ANTISEPTIC Milton T. Bush, Nashville, Tenn, assignor to Mallinckrodt Chemical Works, St. Louis, Mo., a corporation of Missouri No Drawing. Application April 5, 1939, Serial No. 266,127

14 Claims.

This invention relates to antiseptics, and with regard to certain more specific features, to antiseptics particularly adapted for skin sterilization, as in preoperative surgical technique.

Among the several objects of the invention may be noted the provision of antiseptics of the class described which possess an extraordinarily high ability to sterilize in vivo; the provision of antiseptics of the class described which utilize, as their chief active ingredient, an alkyl mercuric salt; the provision of antiseptics of the class described which are free of harmful effects; and the provision of a method of antisepsis using new compositions of matter for this purpose. Other objects will be in part obvious and in part pointed out hereinafter.

The invention accordingly comprises the elements and combinations of elements, the proportions thereof, steps and sequence of steps, and features of composition and manipulation, which will be exemplified in the substances, products,

and methods hereinafter described, and the scope of the application of which will be indicated in the following claims.

The present invention is bottomed upon the discovery, by the applicant, of the capability of alkyl mercuric salts, particularly alkyl mercuric halides, to effect an extraordinarily high degree of antisepsis, or sterilization, particularly in connection with preoperative procedures in surgery.

Alkyl mercuric salts have long been known to exist. In fact, it has long been known that such substances find valuable use as seed disinfecting media. Furthermore, the toxicities of several alkyl mercuric salts with respect to microorganisms generally have been reported in the literature.

However, so far as I have been able to determine, no one has ever investigated the antiseptic activity of such salts, particularly under conditions in vivo. I have made such an investigation, as will appear more fully hereinafter, and have, by comparative tests, ascertained the wholly unexpected fact that the antiseptic activity' of alkyl mercuric salts is far greater than substantially any other antiseptic in current use. The antiseptic or sterilizing activity of the alkyl mercuric salts is particularly well demonstrated in the case of skin sterilization, which is a procedure customarily followed in surgery as a prelude to operative measures. Surprisingly, I have found that solutions of these alkyl mercuric salts are outstandingly useful for such preoperative technique, and are substantially totally free from any objectionable effects.

or another.

The problem of skin sterilization, it will be understood, is one involving a peculiarly high and reliable antiseptic activity on the part of the sterilzing agent. This is in part because the antiseptic is obliged to exert its action not only at the surface of the skin to which it is applied, but also for a short distance into the skin; for the deleterious or pathogenic microorganisms encountered in the skin are frequently by no means all at the surface thereof.

Furthermore, for preoperative technique, it is desirable, and almost essential, that the antiseptic be of the bactericidal, rather than the bacteriostatic class. The alkyl mercuric salts are bactericidal, and not merely bacteriostatic.

For a purpose so critical as a preoperative skin sterilizing agent, mere in vitro tests of antiseptic activity afford no good criteria. This is because antisepsis is frequently easily demonstrable in vitro, but turns out, in vivo, to be either impossible, or at least impracticable, for one reason Hence, in determining the suitability of the alkyl mercuric salts as preoperative skin sterilizing agents, my tests were based upon in vivo methods rather than in vitro methods.

In order fully to explain the highly satisfactory antiseptic properties deduced, the precise method for the in vivo testing of the alkyl mercuric salts herein claimed is set forth below. My method of testing is a variation, or improvement, upon the method described by Birkhaug, in the Journal of Infectious Diseases, vol. 53, page 250 et seq. (1933). My method of testing is as follows:

Normal young adult rabbits were strapped firmly to animal. boards. The hair on the belly was quickly and completely removed by first clipping it close to the skin, followed by the application of a thin barium sulphide-flour (1:1) paste. The depilated skin was then washed, taking especial care to remove all the barium sulphide. The animal was anesthetized with NembutaP' administered intraperitoneally. When the belly was thoroughly dry, it was marked off into squares of approximately one square inch each. With aseptic technique, the animal was draped in such a manner as to expose only the depilated area. Organisms were not added to the skin, since in no case was it ever sterilized by depilation. The antiseptic to be used was placed in sterile test tubes, each of which contained a sterile swab. The swab, soaked in antiseptic, was rubbed vigorously over the desired skin square for 25 seconds. This process of rubbing was adopted because I had been able to demonstrate that it enhanced the antiseptic activity of a compound. At the end of 3 minutes, a piece of skin approximately mm. in diameter was removed from the medicated square with sterilized forceps and Stille steel scissors. It was immediately dropped into 100 cc. of infusion broth and incubated at 37 C. As a standard of comparison, from six to twelve squares were treated in an identical manner with 70 per cent ethyl alcohol. A total of no less than 18 squares was obtained on each rabbit. Three pieces of untreated skin were taken from each animal to be certain that barium sulphide had not itself sterilized the skin. The presence of organisms ence" figure of 24.1; and a 7% U. S. P. tincture of iodine shows a difference figure of 33.6. The superiority of the alkyl mercuric salts investigated is thus evident.

In addition to the alkyl mercuric chloride indicated in the above table, I have also tested and found to be possessed of relatively high antiseptic activity, the following alkyl mercuric salts:

1. 0.018 molar solution of methyl mercuric bromide in 80% ethyl alcohol.

2. 0.018 molar solution of ethyl mercuric bromide in 80% ethyl alcohol.

3. 0.2% solution of hexyl mercuric bromide in 80% ethyl alcohol.

was determined at intervals by the development 15 1% Solution of Secondary but mercuric ch1o of a cloudiness in the media. ride in 75% ethyl alcohol Following the observations made at 48 hours, 5 0 16 u the growth was in most cases confirmed by the sol tion of heptyl mercuric bromide m 80% ethyl alcohol. staimng of the organisms according to Grams method The morphology of the organisms pres 2o Salts other than the chlorides and bromides ent was observed and recorded. Any flasks e150 p to have the desired antiseptic D D- which remained clear after 48 hours incubation j l e. t e odides, the sulfates, the were inoculated with from 50 to 1000 organisms nltrates. nd t e hydromdes likewise app r to obtained from an unmedicated skin culture. All Present his act vity. I intend. for pu po es f these inoculated flasks developed a good growth t p s t np to ud t hydroxides of organisms, eliminating the possibility of bacthe l teriostasis. Growth, however, did not always ap- T ehtlseptlc activity eppears to reside in the pear at a uniform rate. No attempt was made P8111011 W e e is an alkyl, and accordto culture anaerobic organisms. mgly any substance wh1ch in water solution will To obviate the possibility of misleading conclupresent such cation 15 Wlthhl the Scope 0f the sions because of animal variation, a minimum of Present lhvehnohtwelve animals was used in testing each antisep- It 15 to be noted that the P PS mercuric Sa ts, tic preparation among the several alkyls investigated, appear for Using the technique described above, I tested some ream to have much the greatest a the antiseptic activity of methyl, ethyl. propyl, septic activity of all of the salts. Note the r fn-butyl, n-amyl, and n-heptyl mercuric 1 ference value of 83.3 for the 0.0036 molar solurides. In each instance, I made up a solution 25% ethyl alcohol as given in the ove of the desired alkyl mercuric salt in aqueous ethyl table- It will accordingly be u de stood that alcohol. For each animal, in order to get a di- D DY mercuric chloride is pp y the p erect comparison, certain of the skin squares were ferred embodiment of the present invention, rubbed not with the solution of the alkyl merhough this is not intended to exclude the other curic salt, but with aqueous alcohol in the same salts as useful. concentration as the solvent for the particular In View Of the above. it Will e Seen that the alkyl mercuric salt under test. The following several objects of the invention are achieved table sets forth the results obtained: and other advantageous results attained.

Med'cated k St d d 1 $2,223? Concen snips S m co p isoh Antiseptic ethyl tration 285%; 2 3g" sterile Percent Methyl-mercuric-chloride 25 0. 0018 5 31. 6 60 l. 6 30. 0 o 70 0. 0036 6 72 91. 7 72 50. 0 41, 7 Ethyl-mercuric-chlorid 25 0. 0018 5 60 33. 0 60 l. 6 31. 4 o 70 0.0030 6 72 83.3 72 47.2 36,1 Propyl-mercuric-chloride. 25 0. 0018 4 48 41. 7 48 0. 0 41. 7

Do 25 0.0030 7 34 84.5 84. 1.2 83.3 a Do"; 10 0. 0030 4 45 81.3 43 27.1 54,2 n-Butyl-mercuric-chloride.. 70 0. 0036 4 48 93. 7 48 47. 9 45. 8 n-Amyl-mercuric-chloride. 70 0. 0036 7 84 97. 6 84 46. 4 51. 2 n-Heptyl-mercuric-chloride 70 0. 0036 4 47 87. 2 47 34. 2 53.0

In the above table, the right-hand column, As many changes could be made in the above headed Difference, shows the numerical difference between the per cent. of sterile ships for the medicated skin snips, on the one hand, and for the unmedicated control skin snips, on the other, and this difference thus comprises a numerical evaluation of the relative antiseptic activities of the compounds investigated. By way of comparison, it may be stated that the identical technique applied to 3% picric acid in 70% ethyl alcohol shows a difference" figure of 18.0; 0.1% mercury oxycyanide in 70% ethyl alcohol shows a difference figure of 3.2; N. N. R. surgical methods and substances and products without departing from the scope of the invention, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

I claim:

1. An antiseptic containing, as an active ingredient thereof, a substance which, in aqueous solution, provides a cation having the typeformula R-Hg where R is an alkyl.

2. A preoperative skin sterilizing agent containing, as an active ingredient thereof, a subtincture of mercurochrome (2%) showsaclifier- 76 stance which, in aqueous solution, provides a cation having the type-formula RHg+, where R is an alkyl. I

3. An antiseptic containing, as an active ingredient thereof, an alkyl'mercuric salt. 4. An antiseptic containing, as an active ingredient thereof, an alkyl mercuric halide.

5. A preoperative skin sterilizing agent containing, as an active ingredient thereof, an alkyl mercuric salt.

6. An antiseptic containing, as an active ingredient thereof, propyl mercuric chloride.

7. A preoperative skin sterilizing agent containing. as an active ingredient thereof, propyl mercuric chloride.

8. The method'of producing antisepsis which comprises applying to the region to be treated a substance-which, in aqueous solution, provides a cation having the type-formula R-Hg+, where R is analkyl.

9. The method of sterilizing living skin which 20 comprises applying to the skin a substance which, in aqueous solution, provides a cation having the type-formula R-Hg where R. is an alkyl. i

10. The method of producing antisepsis which comprises applying pr'opyl mercuric chloride to the region to be treated.

11. The method of sterilizing living skin which comprises applying propyl mercuric chloride to the skin.

12. An antiseptic containing as an active ingredient thereof an alkyl mercuric chloride. 13. As a sterilizing agent an alkyl mercuric compound which provides in solution a cation having the type formula R.Hg+ where R is an alkyl group.

14. As a sterilizing agent propyl mercuric chloride.

MILTON T. BUSH. 

